The present invention relates to the field of photography and, more specifically, to processing apparatus for treating a sheet-like film unit with a low viscosity processing liquid by immersing the film unit in the liquid for a desired processing interval and then removing it therefrom.
The present invention focusses on immersion treating an exposed self-developing film unit with an aqueous alkaline processing liquid to initiate a development and diffusion transfer process. Typically, this type of self-developing film unit is aimed at the commercial and industrial photography market and generally is provided in the larger formats (4.times.5 and 8.times.10) for use in view cameras and the like. However, it will become apparent later that the processing apparatus is not limited in its use to this particular application, but also may be used for a variety of photographic immersion processes including developing, fixing and washing conventional photographic media.
The prior art is replete with processing apparatus for facilitating immersion treatment of a sheet-like film unit. Typically, such apparatus includes a container or tank holding a supply of processing liquid, means for locating the film unit at a submerged treatment position within the tank, and means for withdrawing the wet film unit from the tank while simultaneously squeegeeing or otherwise removing excess liquid therefrom.
While commonly assigned U.S. Pat. Nos. 3,405,617; 3,405,618; and 3,565,519 disclose examples of self-developing cameras that include immersion processing apparatus which are built into the light-excluding environment of the camera housing, thereby permitting direct transfer of the film unit from the exposure position into the liquid container, the processing apparatus embodying the present invention is a stand-alone device for receiving a film unit that has previously been exposed in a separate camera.
Generally, stand-alone immersion processes known in the prior art are designed to be used in a photographic darkroom where the exposed film unit may be safely removed from a holding cassette for transfer to the processing apparatus without concern about fogging by actinic light.
Representative examples of such immersion type film processes may be found in commonly assigned U.S. Pat. No. 3,288,609 and U.S. Pat. Nos. 3,943,539 and 4,361,392.
The first two of these patents disclose processes that are designed to immersion treat a single sheet film unit while the processor disclosed in the last-mentioned patent is configured to treat an exposed negative sheet and thereafter bring it into superposition with a dry positive image-receiving sheet.
Each of these processes utilize a pair of pressure applying rollers to advance the wet film unit out of the tank while applying a compressive pressure thereto to squeegee excess liquid from the treated film unit.
In U.S. Pat. No. 3,943,539, the same rollers also are used to feed the film unit into the tank initially. While the film unit is submerged in the liquid, one end of the film is retained between a lower set of rollers so the film may be retrieved after immersion treatment. If the submerged film unit should somehow slip out of the grasp of the rollers, the operator is obliged to manually raise a film carrier in the tank to feed the upper end of the film unit into the bite of the rollers before it can be withdrawn.
In the processors disclosed in U.S. Pat. No. 4,361,392, the exposed film unit is removed manually from its holding cassette placed on a processor loading ramp and advanced into the tank to locate it at a submerged processing position. The dry image receiving sheet is placed on a sliding tray above the tank. After a suitable processing interval, the operator must manually rotate the exit rollers with a hand crank and simultaneously manually advance a rake device which pushes the wet film unit and the dry image receiving sheet into the bite of the exit rollers.
These prior art immersion processes have several drawbacks that tend to inhibit efficient film processing. The need to take exposed film to a photographic darkroom for processing and having to manually unload the film from the cassette for transfer into the processing apparatus imposes burdonsome constraints on time and also tends to limit mobility. Some of these prior art processing apparatus require more manual manipulation (e.g., rotating the exit rollers while at the same time actuating the film pushing rake to feed the film into the rollers) than is desirable. Also, some of the prior art processes are mechanically complex and therefore relatively expensive.
Therefore, it is an object of the present invention to provide a simply constructed, easy to use, and relatively inexpensive processing apparatus for immersion treating a sheet-like film unit with a processing liquid.
It is another object to provide such a processing apparatus that is configured for daylight or ambient light operation, thereby eliminating the need for it to be operated in a photographic darkroom environment.
Yet another object of the invention is to provide a film holding cassette which is configured to cooperate with structure on the processing apparatus for easily transferring the film unit into the processing liquid without the operator having to manually handle the film unit.
Still another object of the invention is to provide an immersion processing apparatus which is configured to automatically feed the film unit from a submerged treatment position into the bite of a pair of exit pressure applying rollers in response to rotatably driving the rollers, thereby eliminating any requirement for the operator having to effect such film feed manually.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.